[of price or cost] high enough to prevent people from buying.
When the price of something is prohibitive it is so high that it prevents people from buying it. The price of a car is prohibitive if it is too high for most people to buy. A law is prohibitive if it prevents people from doing something.

He thought of going for a new car, but on hearing the price, he thought it was prohibitive and dropped the idea, as he felt he could not afford so much.

The prohibitive cost of gold prevented Ann from buying any gold jewelry. She was content to buy gold coated ornaments.